“History has demonstrated that the financial system over all — not every piece of it, but over all — is a force for good, even if it goes off track from time to time,” Mr. Miller tells a symposium at Columbia University in remarks posted on YouTube. “As we’ve experienced, sometimes this system breaks down.”

But, it turns out, sometimes when the system breaks down, there is money to be made.

Mr. Miller, who arrived at the Treasury after working at Goldman Sachs, described himself as a “recovering banker” in the video.

Today, he has slipped back through the revolving door between Washington and Wall Street. This time, he has gone the other way, in a new company, Silver Bay Realty, which is about to go public. He is back in the investment game and out to make money with a play that was at the center of the financial crisis: American housing.